Eruptions of the Yellowstone volcanic system have included the two largest volcanic eruptions in North America in the past few million years; the third largest was at Long Valley in California and produced the Bishop ash bed.
On the diesel Passat, the TDI badge stands for Turbocharged Direct Injection, which isn't really all that helpful as the gasoline-powered Passat is also turbocharged and also uses direct injection. Volkswagen attempts to clear this up by calling this Passat the Passat TDI Clean Diesel.
Audi claims that the average fuel consumption for the Cope variant with the 2.0 TDI engine is 5.3 liters which achieves a CO2 emissions rating of 139 gram. The Roadster TDI achieves an average of 51.4 mph and CO2 of 144 gram.